tests: use composer to autoload

phpunit.xml

@@ -1,4 +1,4 @@
-<phpunit bootstrap="tests/autoload.php">
+<phpunit bootstrap="vendor/autoload.php">
   <testsuites>
     <testsuite name="helpers">
       <directory>tests</directory>

tests/autoload.php

@@ -1,10 +0,0 @@
-<?php
-
-// report all possible php errors
-error_reporting(-1);
-
-require_once(__DIR__ . '/../ArrayHelper.php');
-require_once(__DIR__ . '/../DateTimeHelper.php');
-require_once(__DIR__ . '/../Image.php');
-require_once(__DIR__ . '/../PropertyAccessTrait.php');
-require_once(__DIR__ . '/../StringHelper.php');